Bought a van! Now what? 12 or 48 volt?

[Ariel188]

Hello everyone!

So I plan to have a large build in my Sprinter 170 ext dually.

I an planning on this build (done by my van builder who has only done 12 volt small systems....)
On roof 700-800 watts of walkable solar panels. https://www.custommarineproducts.com/semi-rigid-walk-on-marine-solar-panels.html
and 800-1200 amp batteries (dont know which one yet.)

I wanted to do 48 volt but everyone is saying I should do 12.....I am confused I need more opinions please.

I will have rixan diesel heater, cruise N comfort AC at 12 or 48 volt, induction stove, breville oven, washer, use a vitamix blender daily, instapot, food processor, gaming computer, I plan to buy a SECOND alternator (280 nations) so I need a system that will charge as fast as possible with the second alternator. I will also have shore power connection, and even EV charger port. I will be hiring a builder to build my van and do the solar. He has never done a 48 volt thou. I have allocated 20K for my solar system (but would love to NOT spend that much, to have an amazing system that is limit less) so I never have to struggle again with power like I do now in my 42 ft RV with 48 volt put in by someone with no experience........ Thank you for the thoughts, advice, and opinions to help a girl out! ;-)

 

[krby]

The general rule of thumb is you can do up to ~3000W (some say 2000W) on 12V. If you have a bunch of 12V equipment already, aren't going to exceed 2000W then that may be easiest. However, 48V systems are generally "the new hotness" so lots of gear is coming out to support 48V. If you have gear that can on 48V, you'll end up using smaller gauge wire and generally end up with less loss overall (because loss in wiring and connections is a function of current and 48V systems use 1/4 the current for the same power in watts as 12V systems.


Do you plan to run most things off an inverter? Or will you have a bunch of DC devices? If you think you'll run mostly DC, IMO it will be easier to find 12V devices than 24 or 48V

 

[DIYrich]

You can buy lots of stuff that runs off 12v. If you need more than 3kW of power, then you might need to upgrade voltage to keep amps down. At 48v, you are probably conceeding an inverter to convert power to 120v ac, and running stuff off that.

 

[time2roll]

Van? I would be at 12v. Works fine in my RV trailer. Or are you planning 1000+ watts solar and 3000+ watts inverter? 12v accessories are so much easier to find over 48v.

 

[justinm001]

Cruisencomfort will be much better at 48v. Cheaper wiring and more btu I'd assume. The problem you'll have is with a 48v alternator. You'd need to either get one off a jeep ev or a Balmer ($$$) then control witha wakespeed ws500 or similar. 1 or more 48-12 victron dc converters will easily convert to power any 12v accessories.

I have a 5k 12v inverter and dual 5k 48v inverters and my 48v system works so much better. 12v has such a narrow range as can't charge over 15v where 48v is much larger and charge to 57v+

 

[Isaac-1]

I tend to feel you are right on the cusp of either one being a practical choice, therefore I would lean 12V dues to easier parts availability, etc. My rule of thumb is that 48V make sense at over 800 to 1,000 watts of solar panels, or over 3,000 watt combined total discharge rate.

 

[Dave in AZ]

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

Most of the power use items listed are AC. Op expressed a desire to use them but not run out of power. Power source will be 800w solar on roof, a 2nd alternator, and shore power.

rixan diesel heater - 12v 50w
cruise N comfort AC at 12v 55A or 48volt 16A
Induction stove 1800w, 120vac
breville oven 1800w, 120vAC
washer ? 120vac
vitamix blender 120vac, 12A 1440w. But induction motor needs >2000w to start.
instapot 120vac, 700-1500w
food processor 120vac, 1500-3000w startup
gaming computer 120vac, ? 1000w?

The diesel heater and airco can be 12v. Airco large draw at 55A continuous.

All rest are cooking, 120vac, 1500w but several will need 2500 to 3000 w to run hard motor starts, blender and food processor. Recommend 3000w inverter. This, along with constant airco power, drives 48v system.

The airco in hot temps pulls 800w continuous. 800w solar on roof can't keep up. Shore power or dedicated alternator work when driving or plugged in, otherwise batteries. To run airco 12 hrs off batteries requires 9600wh of batteries. In a 48v system, that is 48v 200ah. In order to also run cooking devices for a meal, add 1500wh, 32ah more battery. For gaming computee, figure 200w power, 6 hrs, another 1200wh, 25ah more battery. So, 257ah of 48v battery or 12,300wh. Thats just 12 hrs AIrco use...

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

However... honestly I would lean towards 24v! The airco is almost as efficient at 24v.
alternator much easier to get at 24v.
All fuses, breakers, and switches MUCH MUCH easier to get at 24v vs 53v or so.
Wiring ampacity benefits are still good at 24v for this wattage level.

The problem with 48v systems that no one ever mentions is that Bluesea cutoff switchs and fuseboxes etc are not rated for 48v working charge voltages etc. To actually build the system, parts needed, 48v-56v sucks. People claim, "there are more 48v use items showing up...", but that is not what is needed here, it is 48 to 56v rated parts to build mobile system. All the usage items Op wants are 120vac, there is zero requirement to find expensive 48v replacement devices.

If you wanted to use a 48v all in one system, reduces parts issues but at cost of apparently endless software failures...there are 50 posts a day here of folks whose 48v EG systems won't work. And endless posts of trying to figure out firmware and software settings that are nerfing the system.

 

 

[justinm001]

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

Most of the power use items listed are AC. Op expressed a desire to use them but not run out of power. Power source will be 800w solar on roof, a 2nd alternator, and shore power.

rixan diesel heater - 12v 50w
cruise N comfort AC at 12v 55A or 48volt 16A
Induction stove 1800w, 120vac
breville oven 1800w, 120vAC
washer ? 120vac
vitamix blender 120vac, 12A 1440w. But induction motor needs >2000w to start.
instapot 120vac, 700-1500w
food processor 120vac, 1500-3000w startup
gaming computer 120vac, ? 1000w?

The diesel heater and airco can be 12v. Airco large draw at 55A continuous.

All rest are cooking, 120vac, 1500w but several will need 2500 to 3000 w to run hard motor starts, blender and food processor. Recommend 3000w inverter. This, along with constant airco power, drives 48v system.

The airco in hot temps pulls 800w continuous. 800w solar on roof can't keep up. Shore power or dedicated alternator work when driving or plugged in, otherwise batteries. To run airco 12 hrs off batteries requires 9600wh of batteries. In a 48v system, that is 48v 200ah. In order to also run cooking devices for a meal, add 1500wh, 32ah more battery. For gaming computee, figure 200w power, 6 hrs, another 1200wh, 25ah more battery. So, 257ah of 48v battery or 12,300wh. Thats just 12 hrs AIrco use...

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

However... honestly I would lean towards 24v! The airco is almost as efficient at 24v.
alternator much easier to get at 24v.
All fuses, breakers, and switches MUCH MUCH easier to get at 24v vs 53v or so.
Wiring ampacity benefits are still good at 24v for this wattage level.

The problem with 48v systems that no one ever mentions is that Bluesea cutoff switchs and fuseboxes etc are not rated for 48v working charge voltages etc. To actually build the system, parts needed, 48v-56v sucks. People claim, "there are more 48v use items showing up...", but that is not what is needed here, it is 48 to 56v rated parts to build mobile system. All the usage items Op wants are 120vac, there is zero requirement to find expensive 48v replacement devices.

If you wanted to use a 48v all in one system, reduces parts issues but at cost of apparently endless software failures...there are 50 posts a day here of folks whose 48v EG systems won't work. And endless posts of trying to figure out firmware and software settings that are nerfing the system.

 

The cruisencomfort 12v is 10k btu vs the 48v which is 12kbtu. Much larger.

I thought all bluesea and everything else is rated in nominal voltage and much seems to support 48v systems. I run MRBF Blue sea fuse blocks and rated at 58v. ATO/ATC (blade type) fuses only support 32volts. But I don't see why people like those bluesea on/off switches when you can just get a mini-din breaker that not only works as a on/off but provides OC protection. I'd take this over a bluesea switch https://a.co/d/2CWvPN1

48v alternators are becoming much more popular. To pull 3kw from 12v you're pushing 4/0 cable (230a of 260a) where in 48v you're well under 6ga (56a of 75a).

 

[Isaac-1]

I admit pulling 3KW from 12V using 4/0 is a limitation, however in most setups that is only running from the battery to an inverter located perhaps 36 inches or less away, in other words not that big of deal either in weight or cost penalty, such a pair of 3 ft cables will weigh in at around 4 pounds of weight and around $50 for pre-built quality all copper fine stranded cables. Off set this vs the complexity, cost and weight of 48V to 12V converters to run your 12V LED lighting, added cost of 48V equipment, etc. and I just don't see it as that big of penalty that some people make it out to be. Sure on larger systems you do have to raise voltage to be practical, the question is at what point do you draw the line

 

[justinm001]

I admit pulling 3KW from 12V using 4/0 is a limitation, however in most setups that is only running from the battery to an inverter located perhaps 36 inches or less away, in other words not that big of deal either in weight or cost penalty, such a pair of 3 ft cables will weigh in at around 4 pounds of weight and around $50 for pre-built quality all copper fine stranded cables. Off set this vs the complexity, cost and weight of 48V to 12V converters to run your 12V LED lighting, added cost of 48V equipment, etc. and I just don't see it as that big of penalty that some people make it out to be. Sure on larger systems you do have to raise voltage to be practical, the question is at what point do you draw the line

OP wants 1200ah of batteries so 3 rack batteries (300ah at 48v). 3ft seems crazy, you're likely going to need at least 10ft to connect the batteries together then to a distribution buss then to the inverter.

But thats not really the point. You're always going to have a limitation and with a 20k budget you don't want a couple hundred to be the difference between running 3000w and 13000w which is only limited by the battery.

A 150/100 victron mppt is $511 (1450w 12V) and a 150/35 is $184 (2000w at 48V). An Orion 48/12 20amp converter is $113. OP would save $214 just from the mppt if she only needs 20a in 12V. Could buy a 2nd and still save money.

Pumping 250amps through any size cable is a LOT of power in a moving vehicle. Everything just seems so much easier and safer when you can keep it all under 100amps in most circumstances. I always feel everything electrical should be overbuilt with 20-30% headroom to account for environmental changes and things being non-optimal. 12V will easily run 2000w (150a) with proper wiring but pushing it to its max in a vehicle that's moving with vibrations and possibly in tight spaces just doesn't seem like a good idea.

 

[Isaac-1]

With all due respect here, I can see your point on larger RV's but we are talking about what appears to be a Sprinter van based on avatar photo, so roof area will be limited to about 4x15 feet (roof rails on most sprinters are about 51 inches apart). Realistically you are not fitting over 1,000 watts of solar on this, likely less, highest amount I find for Sprinter roof mounted solar online is 875 watts, most are more like 800 watts, with the OP targeting 700-800 watts worth of panels which is within the practical sizing range though slightly over sized for the Victron 100/50 that sells for $184 on a 12V system. As to 3 ft cable length a lot depends on mounting configuration, which will be tight in a Sprinter regardless, but is certainly doable for a pair of 400AH 12V case mount not rack batteries with terminal post near one end, sat side by side, or end to end with terminals facing each other (maybe something like a pair of 460AH LiTime Power Monster batteries for a total of 920AH, each with a 250A BMS), I admit 3 batteries makes it more challenging. Note OP said 800-1200 AH. My point here is fitting all this in a Sprinter is going to be one of the prime limitations, not only for space, but also weight carrying capacity, etc., in a larger RV with room for growth maybe 48V makes more sense.

 

[Reed Cole]

In a modern vehicle I don't think the vibrations are that big of a concern, just from personal experience, so take it with a grain of salt, but also it wouldn't be that hard to mitigate.

With 800-1200ah battery at 12v I would be concerned about how long it would take to charge from the alternator. Which is pretty critical for a van system since you are limited on how many panels you can add. If you are always having to plugin into shore power in the winter or wretchedly carry a generator with you that is a significant decrease in a quality of life.

I don't know anything about 48v alternators in practice but in theory that would be a much faster, safer way to charge a battery bank of that capacity, 200-300ah at 48v.

 

[justinm001]

With all due respect here, I can see your point on larger RV's but we are talking about what appears to be a Sprinter van based on avatar photo, so roof area will be limited to about 4x15 feet (roof rails on most sprinters are about 51 inches apart). Realistically you are not fitting over 1,000 watts of solar on this, likely less, highest amount I find for Sprinter roof mounted solar online is 875 watts, most are more like 800 watts, with the OP targeting 700-800 watts worth of panels which is within the practical sizing range though slightly over sized for the Victron 100/50 that sells for $184 on a 12V system. As to 3 ft cable length a lot depends on mounting configuration, which will be tight in a Sprinter regardless, but is certainly doable for a pair of 400AH 12V case mount not rack batteries with terminal post near one end, sat side by side, or end to end with terminals facing each other (maybe something like a pair of 460AH LiTime Power Monster batteries for a total of 920AH, each with a 250A BMS), I admit 3 batteries makes it more challenging. Note OP said 800-1200 AH. My point here is fitting all this in a Sprinter is going to be one of the prime limitations, not only for space, but also weight carrying capacity, etc., in a larger RV with room for growth maybe 48V makes more sense.

That mppt only does 700w for 12v and op would want one that does over 800w if she's planning on 800w.

But even so we're talking under $100 difference for a dc-dc converter to have much more stable voltage and smaller gauge wiring across the board. This means smaller distribution block, smaller gauge from MPPT to inverter and to the dc-dc converter.

My 48v inverters are quite a bit smaller than my 12v for identical models. Also they were close to a grand cheaper $2900 vs $3700. Run quieter too.

There's no benefit for 12v and the 48v benefits become more and more apparent with the more devices and power you have

 

[Reed Cole]

Discounted Secondary Alternator Power System Bundle for Vans and RVs

Powerful electrical system combines a 280 amp alternator with an advanced regulator and Victron Smart Lithionics batteries to power your van or adventure rig.

www.vanlifeoutfitters.com

A quick search showed me this bundle of all the components you might need for a 48v system including the alternator, not saying you should buy this or not but it's quick way to get an idea of most everything you would need except for solar panels.

 

[justinm001]

Discounted Secondary Alternator Power System Bundle for Vans and RVs

Powerful electrical system combines a 280 amp alternator with an advanced regulator and Victron Smart Lithionics batteries to power your van or adventure rig.

www.vanlifeoutfitters.com

A quick search showed me this bundle of all the components you might need for a 48v system including the alternator, not saying you should buy this or not but it's quick way to get an idea of most everything you would need except for solar panels.

BTW that alternator is rated at 100amps, almost 5000w of power when driving. OP couldn't get close to this on a 12v system says their 12v verson gets 220a max (2500w).

This makes a huge difference because it means she can charge entire system in 2 hours just by driving.... or 4 by just running the engine parked.

 

[Isaac-1]

That mppt only does 700w for 12v and op would want one that does over 800w if she's planning on 800w.

An MPPT only doing 700 watts max output with 800 watts worth of panels is not typically an issue in van / RV applications with flat mounted panels as due to lack of tilt the number of hours per day that they achieve rated output is much lower, in other words those 800 watt panels are likely only outputting 800 watts perhaps an hour per day. Even Victron's blog guidelines talk about oversizing panels compared to MPPT by up to 130% here (about half way down the page) https://www.victronenergy.com/blog/...ar-modules-to-the-new-mppt-charge-regulators/

ps you have a good point on the alternator, though Sprinters with their DPF equipped diesel engines should never be left at idle for more than a few minutes, Mercedes even says not to run at high idle for over 2 hours. Here is a link on another forum talking about this specific problem with using second alternators on Sprinters https://sprinter-source.com/forums/index.php?threads/87243/post-901571

 

[justinm001]

An MPPT only doing 700 watts max output with 800 watts worth of panels is not typically an issue in van / RV applications with flat mounted panels as due to lack of tilt the number of hours per day that they achieve rated output is much lower, in other words those 800 watt panels are likely only outputting 800 watts perhaps an hour per day. Even Victron's blog guidelines talk about oversizing panels compared to MPPT by up to 130% here (about half way down the page) https://www.victronenergy.com/blog/...ar-modules-to-the-new-mppt-charge-regulators/

In summer I routinely get 2000w from my 1800w of panels in summer. Might be just 1 hour or so per day.

I just don't see the point in building a quality system then skipping on a couple cheap parts to limit yourself.

Overpanelling makes a ton of sense when building a home array and maximizing profit but not in an rv setup where every watt matters especially mid day

 

[Isaac-1]

I guess we just differ a bit in design choices, personally in a RV situation, I prefer to have native 12V deep cycle batteries, preferably at least 2 of them for redundancy, that way in case of a failed battery / failed BMS things will still work, and such a component failure would not ruin a trip. The same can be said about avoiding having a 48V-12V converter, as most of my important DC loads are 12V loads, such as LED lighting, fans, USB chargers, furnace blower, 12V portable freezer, etc. I am also not afraid of large diameter DC wires, but that may be due to my background around motive power equipment (electric fork lifts, etc.)

 

[justinm001]

I guess we just differ a bit in design choices, personally in a RV situation, I prefer to have native 12V deep cycle batteries, preferably at least 2 of them for redundancy, that way in case of a failed battery / failed BMS things will still work, and such a component failure would not ruin a trip. The same can be said about avoiding having a 48V-12V converter, as most of my important DC loads are 12V loads, such as LED lighting, fans, USB chargers, furnace blower, 12V portable freezer, etc. I am also not afraid of large diameter DC wires, but that may be due to my background around motive power equipment (electric fork lifts, etc.)

This is kinda more of a case for using 48v. You can easily add any 12v battery as a buffer. Also can get a cheap ac to dc 12v adapter/charger as a backup.

 

[Ariel188]

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

Most of the power use items listed are AC. Op expressed a desire to use them but not run out of power. Power source will be 800w solar on roof, a 2nd alternator, and shore power.

rixan diesel heater - 12v 50w
cruise N comfort AC at 12v 55A or 48volt 16A
Induction stove 1800w, 120vac
breville oven 1800w, 120vAC
washer ? 120vac
vitamix blender 120vac, 12A 1440w. But induction motor needs >2000w to start.
instapot 120vac, 700-1500w
food processor 120vac, 1500-3000w startup
gaming computer 120vac, ? 1000w?

The diesel heater and airco can be 12v. Airco large draw at 55A continuous.

All rest are cooking, 120vac, 1500w but several will need 2500 to 3000 w to run hard motor starts, blender and food processor. Recommend 3000w inverter. This, along with constant airco power, drives 48v system.

The airco in hot temps pulls 800w continuous. 800w solar on roof can't keep up. Shore power or dedicated alternator work when driving or plugged in, otherwise batteries. To run airco 12 hrs off batteries requires 9600wh of batteries. In a 48v system, that is 48v 200ah. In order to also run cooking devices for a meal, add 1500wh, 32ah more battery. For gaming computee, figure 200w power, 6 hrs, another 1200wh, 25ah more battery. So, 257ah of 48v battery or 12,300wh. Thats just 12 hrs AIrco use...

Complicated, huge power use system. OP stated use drives > 3000w usage at once, potentially often.

However... honestly I would lean towards 24v! The airco is almost as efficient at 24v.
alternator much easier to get at 24v.
All fuses, breakers, and switches MUCH MUCH easier to get at 24v vs 53v or so.
Wiring ampacity benefits are still good at 24v for this wattage level.

The problem with 48v systems that no one ever mentions is that Bluesea cutoff switchs and fuseboxes etc are not rated for 48v working charge voltages etc. To actually build the system, parts needed, 48v-56v sucks. People claim, "there are more 48v use items showing up...", but that is not what is needed here, it is 48 to 56v rated parts to build mobile system. All the usage items Op wants are 120vac, there is zero requirement to find expensive 48v replacement devices.

If you wanted to use a 48v all in one system, reduces parts issues but at cost of apparently endless software failures...there are 50 posts a day here of folks whose 48v EG systems won't work. And endless posts of trying to figure out firmware and software settings that are nerfing the system.

 

So for delay, my internet has been out since right after I made this post and it will be out again soon! ;-(

WOW you are amazing!!! Thank you for being so detailed with the power everything consumes! Awesome! I could not even find a lot of this info!!

You referred to "Airco" a lot, and I have no clue what that is?

Also the crusin N comfort AC, DOES make a 24 volt version of their AC unit as well. In my reaseach of van solar systems, it seemed the consensus was to stay away from 24 volt, and to either 12 or 48...so confusing.

Thank you for your thoughts on this matter!